/*
 * Copyright (c) 2007, 2015, Oracle and/or its affiliates. All rights reserved.
 * ORACLE PROPRIETARY/CONFIDENTIAL. Use is subject to license terms.
 */
/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements. See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership. The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at
 *
 * http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied. See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */
package com.sun.org.apache.xml.internal.security.transforms.implementations;

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.OutputStream;

import javax.xml.XMLConstants;
import javax.xml.transform.Source;
import javax.xml.transform.Transformer;
import javax.xml.transform.TransformerConfigurationException;
import javax.xml.transform.TransformerException;
import javax.xml.transform.TransformerFactory;
import javax.xml.transform.dom.DOMSource;
import javax.xml.transform.stream.StreamResult;
import javax.xml.transform.stream.StreamSource;

import com.sun.org.apache.xml.internal.security.exceptions.XMLSecurityException;
import com.sun.org.apache.xml.internal.security.signature.XMLSignatureInput;
import com.sun.org.apache.xml.internal.security.transforms.Transform;
import com.sun.org.apache.xml.internal.security.transforms.TransformSpi;
import com.sun.org.apache.xml.internal.security.transforms.TransformationException;
import com.sun.org.apache.xml.internal.security.transforms.Transforms;
import com.sun.org.apache.xml.internal.security.utils.XMLUtils;
import org.w3c.dom.Element;

/**
 * Class TransformXSLT
 *
 * Implements the <CODE>http://www.w3.org/TR/1999/REC-xslt-19991116</CODE>
 * transform.
 *
 * @author Christian Geuer-Pollmann
 */
public class TransformXSLT extends TransformSpi {

  /**
   * Field implementedTransformURI
   */
  public static final String implementedTransformURI =
      Transforms.TRANSFORM_XSLT;

  static final String XSLTSpecNS = "http://www.w3.org/1999/XSL/Transform";
  static final String defaultXSLTSpecNSprefix = "xslt";
  static final String XSLTSTYLESHEET = "stylesheet";

  private static java.util.logging.Logger log =
      java.util.logging.Logger.getLogger(TransformXSLT.class.getName());

  /**
   * Method engineGetURI
   *
   * @inheritDoc
   */
  protected String engineGetURI() {
    return implementedTransformURI;
  }

  protected XMLSignatureInput enginePerformTransform(
      XMLSignatureInput input, OutputStream baos, Transform transformObject
  ) throws IOException, TransformationException {
    try {
      Element transformElement = transformObject.getElement();

      Element xsltElement =
          XMLUtils.selectNode(transformElement.getFirstChild(), XSLTSpecNS, "stylesheet", 0);

      if (xsltElement == null) {
        Object exArgs[] = {"xslt:stylesheet", "Transform"};

        throw new TransformationException("xml.WrongContent", exArgs);
      }

      TransformerFactory tFactory = TransformerFactory.newInstance();
      // Process XSLT stylesheets in a secure manner
      tFactory.setFeature(XMLConstants.FEATURE_SECURE_PROCESSING, Boolean.TRUE);

            /*
             * This transform requires an octet stream as input. If the actual
             * input is an XPath node-set, then the signature application should
             * attempt to convert it to octets (apply Canonical XML]) as described
             * in the Reference Processing Model (section 4.3.3.2).
             */
      Source xmlSource =
          new StreamSource(new ByteArrayInputStream(input.getBytes()));
      Source stylesheet;

            /*
             * This complicated transformation of the stylesheet itself is necessary
             * because of the need to get the pure style sheet. If we simply say
             * Source stylesheet = new DOMSource(this.xsltElement);
             * whereby this.xsltElement is not the rootElement of the Document,
             * this causes problems;
             * so we convert the stylesheet to byte[] and use this as input stream
             */
      {
        ByteArrayOutputStream os = new ByteArrayOutputStream();
        Transformer transformer = tFactory.newTransformer();
        DOMSource source = new DOMSource(xsltElement);
        StreamResult result = new StreamResult(os);

        transformer.transform(source, result);

        stylesheet =
            new StreamSource(new ByteArrayInputStream(os.toByteArray()));
      }

      Transformer transformer = tFactory.newTransformer(stylesheet);

      // Force Xalan to use \n as line separator on all OSes. This
      // avoids OS specific signature validation failures due to line
      // separator differences in the transformed output. Unfortunately,
      // this is not a standard JAXP property so will not work with non-Xalan
      // implementations.
      try {
        transformer.setOutputProperty("{http://xml.apache.org/xalan}line-separator", "\n");
      } catch (Exception e) {
        log.log(java.util.logging.Level.WARNING,
            "Unable to set Xalan line-separator property: " + e.getMessage());
      }

      if (baos == null) {
        ByteArrayOutputStream baos1 = new ByteArrayOutputStream();
        StreamResult outputTarget = new StreamResult(baos1);
        transformer.transform(xmlSource, outputTarget);
        return new XMLSignatureInput(baos1.toByteArray());
      }
      StreamResult outputTarget = new StreamResult(baos);

      transformer.transform(xmlSource, outputTarget);
      XMLSignatureInput output = new XMLSignatureInput((byte[]) null);
      output.setOutputStream(baos);
      return output;
    } catch (XMLSecurityException ex) {
      Object exArgs[] = {ex.getMessage()};

      throw new TransformationException("generic.EmptyMessage", exArgs, ex);
    } catch (TransformerConfigurationException ex) {
      Object exArgs[] = {ex.getMessage()};

      throw new TransformationException("generic.EmptyMessage", exArgs, ex);
    } catch (TransformerException ex) {
      Object exArgs[] = {ex.getMessage()};

      throw new TransformationException("generic.EmptyMessage", exArgs, ex);
    }
  }
}
